Objective

Hello guys welcome to MAE Learning and in this tutorial, we will learn and develop a Simulink-based “Engine Cooling Fan Control” which follow below conditions:

Design and simulate a cooling fan control system that automatically adjusts its speed based on temperature. The control logic is:

  • Fan OFF   if Temperature < 90°C
  • Fan Speed 1 if 90°C ≤ Temperature < 100°C
  • Fan Speed 2 if Temperature ≥ 100°C

Control Logic

  1. Inputs: Temperature signal (°C)
  2. Outputs: Fan status (0 = OFF, 1 = Speed 1, 2 = Speed 2)
  3. Decision Flow:
    • If Temp ≥ 100 → Fan Status = 2
    • Else if Temp ≥ 90 → Fan Status = 1
    • Else → Fan Status = 0

Simulink Modelling Approach

  1. Input Block:
    • Use a Signal Builder, Step Input, or Constant block for temperature simulation.
  2. Relational Operators:
    • Compare temperature against thresholds (≥100 and ≥90).
  3. Switch Blocks:
    • First switch checks for Temp ≥ 100 (sets Speed 2).
    • Second switch checks for Temp ≥ 90 (sets Speed 1 if Speed 2 condition is false).
  4. Output Display:
    • Use Scope or Display block to monitor fan status in real time.

Logic Design

Engine Cooling Fan Control

Model Behavior

  • Subsystem Layout:
    • Temperature input is branched into two relational checks (≥100 and ≥90).
    • Switches determine the appropriate fan status based on comparisons.
  • Fan Status Transitions:
    • Temp < 90 → OFF (0)
    • Temp ≥ 90 but < 100 → Speed 1 (1)
    • Temp ≥ 100 → Speed 2 (2)

Simulation Graph

  • Simulation plots show temperature changes alongside fan status transitions.

Practical Insights

  • Threshold-based control is widely used in HVAC systems, electronics cooling, and automation.
  • Simulink’s block-based approach makes it easy to adjust thresholds or add more fan speed levels.
  • Logic is modular and can be reused for similar control applications.